Video presentation on the QRP Labs QDX 5-watt Digital Transceiver

Four Days in May (FDIM) is an annual QRP convention that is held in Dayton, Ohio. A series of talks are usually given and for the 2022 event, there was an interesting presentation given by Hams Summers (G0UPL) about his new QDX transceiver kit.

This is a 5-watt radio for the 80m, 40m, 30m and 20m bands and is designed for digital modes like FT8. The basic kit currently retails for just $69 but there may be additional costs like import duties. It is still a very cost effective way of getting on the bands especially when you consider how many main brand radios costing $1000++ must be sitting on one frequency doing FT8 day after day.

Hans writes on his website... "QDX is suitable only for single tone FSK modes, which covers the majority of digital modes in use today. This includes everything in WSJT-X, JS8Call, some fldigi modes e.g. RTTY, Olivia and more. QDX is not suitable for on/off keyed modes such as CW because it does not have click-reducing RF envelope shaping; furthermore it is not suitable for phase shift keyed modes such as PSK31 or modes involving multiple concurrent tones such as WinLink,"

The QDX is supplied with the surface mount parts already on the PCB but some level of experience is still required to build and assemble this kit. I don't think it's for absolute beginners.

The power output versus the supply voltage is shown above. As the frequency is relatively low... 3.5 MHz to 14 MHz... the performance of the output stage is pretty good.

Hans did mention that there are plans for a similar radio covering 20m to 10m ...14 MHz to 28 MHz... and the challenge then will be to have a reasonable output at the higher frequencies.

Demand for this kit has been huge so check on the QRP Labs website for availability. There is also a lot more information about the radio on that site.

The presentation itself covers the basics of digital modes before exploring what is going on in the QDX radio.

The video of the presentation which was only put up on YouTube on the 14th of November 2022 is about an hour long but the audio level is very low. I had to use headphones to listen to it.

QRP-Labs release a 50 watt amplifier for their CW QCX Transceiver

The QCX cw transceiver from QRP-Labs is one of the most popular kits for radio amateurs on the market and sells for just $49. It comes in single band versions from 80m to 17m. Earlier in 2019, they sold their 8,000th kit which just testifies how popular this little 5 watt radio is.

QRP-Labs have now announced that they are releasing an accompanying amplifier which is capable of 50 watts.

Some of the key features...
Designed for the QCX CW transceiver kit

Up to 50W power output on 40m with 20V supply, falling to around 25W at 13.8V supply
50-ohm input and output
Fast clean solid-state Tx/Rx switching provides full break-in operation (QSK)
Can be built for one of 40, 30m or 20m bands with the supplied components (or other bands with suitable choice of Low Pass Filter components)
Uses two low-cost IRF510 transistors as the power amplifier in push-pull configuration
Recommended amplifier operation in Class C (Not suitable for SSB)
On-board 7-element Low Pass Filter for harmonic attenuation
Standard inexpensive components throughout (easy to replace)

The chart below shows how the output power is dependent on the supply voltage and the frequency.

The price of the amplifier is just $29.50. There is also an optional enclosure for an additional $16.

For more info, go to https://qrp-labs.com/50wpa.html

QRP-Labs sell their 8000th QCX CW Transceiver

QRP-Labs have just announced that they have sold their 8,000th QCX CW Transceiver kit on the 31st of July 2019.

The kit which sells for just $49 is a high performance single band CW transceiver and was first launched in August of 2017.

These are just some of the features...

Choice of single band, 80, 60, 40, 30, 20 or 17m
Approximately 3-5W CW output (depending on supply voltage)
Class E power amplifier, transistors run cool… even with no heatsinks
7-element Low Pass Filter ensures regulatory compliance
High performance receiver with at least 50dB of unwanted sideband cancellation
200Hz CW filter with no ringing
Iambic keyer or straight key option included in the firmware
Simple Digital Signal Processing assisted CW decoder, displayed real-time on-screen
Frequency presets, VFO A/B Split operation, RIT, configurable CW Offset

More info here... http://qrp-labs.com/qcx.html

The QSX SSB model is currently under development and should prove to be even more popular.

New High-Performance 10 watt 10 Band SSB/CW kit from QRP-LABS...

Update May 2019 : Hans Summers G0UPL of QRP Labs gave a presentation at the recent Hamvention in Dayton, Ohio about his new QSX transceiver.

The links are up on the QRP Labs website HERE

Just open the slides in PDF format and listen to the podcast from about 51 minutes in.

*****

Original post August 2018

Hans Summers G0UPL of QRP-LABS produces a range of really stunning high quality kits at very modest prices. His current QCX model which is a 5 watt mono-band CW transceiver has sold over 5000 units to date and sells for just $49.

QRP Labs announce new 10 watt HF amplifier

QRP Labs have just released a new 10 watt amplifier for the HF bands and it looks pretty impressive considering the modest price of $26.

According to the release notes, it can comfortably produce 10 Watts from a 12V supply and will not overheat even on continuous 100% duty-cycle operation.

It has 26dB gain with +/- 1dB gain flatness from 2 to 30MHz. This means that it requires just 25 milliwatts of drive to achieve 10 watts output.

It has lower gain above 30 MHz with a potential output of 4 watts on 50 MHz and 1.7 watts on 70 MHz.

There are no Surface Mount Components (SMD) to solder and a number of small transformers need to be wound.

Key Features:
10W output from 2 to 30MHz, using 12V Supply
Generously-sized heatsink, will not overheat even on continuous 100% duty-cycle modes
2-stage amplifier provides 26dB of gain
Push-pull driver and push-pull finals, for high linearity and low harmonic content
+/- 1dB gain flatness from 2 to 30MHz
4dB down at 6m (50MHz) and 8dB down on 4m (70MHz)
Standard 50-ohm input and output
Through-hole plated PCB, all through-hole components (no Surface Mount Devices)
Standard inexpensive components throughout
Tested for 1 hour at full-power 10W, 100% continuous duty-cycle with no forced air cooling
Tested for 15 minutes at 20W, 100% continuous duty-cycle with no forced air cooling
Tested at 20V supply
Tested into open load, shorted load and various mismatches without instability (oscillation)

http://qrp-labs.com/linear

Amplifier with supplied heatsink.

Presentation : "Modern QRP Rigs and the Development of the QCX CW Transceiver kit" by Hans Summers

Every year, the QRP Amateur Radio Club International hosts a QRP conference called Four Days in May (FDIM) in the United States. This year (2018), Hans Summers G0UPL of QRP-LABS made a presentation titled "Modern QRP Rigs and the Development of the QCX CW Transceiver kit".

He introduced three main themes, all based around use of the QCX CW transceiver as an example of a practical implementation and which he describes as follows :

Better architectures than the SA602 -> crystal filter -> SA602 superhet which I am calling the "cold war sandwich", since it has been around since the 1980's and heavily copied by amateurs ever since
Modern oscillators, in particular the Si5351A, which make it easy and cheap to make a crystal-locked flexible and precise oscillator
Use of microcontrollers in your projects.

The slides for the presentation are here... http://qrp-labs.com/images/news/dayton2018/seminar.pdf

The audio of the presentation can be found on the Ham Radio Workbench website.... https://www.hamradioworkbench.com/podcast/2018-qrp-arci-fdim-hans-summers-g0upl-and-dr-jack-purdum-w8tee

Listen to the podcast from 1h 20m to 2h 02m and refer to the slides during the talk.

The full 41 pages of the FDIM conference proceedings booklet from Hans Summers can be viewed here... http://qrp-labs.com/images/news/dayton2018/fdim2018.pdf

Links...
1) http://www.qrp-labs.com